1. Field of the Invention
The present invention relates to a probing technique of TFT-LCD (Thin-Film Transistor Liquid Crystal Display), and in particular to a pin structure of a probing device for a TFT-LCD substrate.
2. The Related Arts
Liquid crystal display (LCD) has a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and is thus widely used. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal display panel and a backlight module. The operation principle of the liquid crystal display panel is that liquid crystal polymer molecules are interposed between two parallel glass substrates and the liquid crystal molecules are controlled to change direction by application of electricity to the glass substrates in order to refract light emitting from the backlight module for generating images.
A liquid crystal display panel is generally composed of an upper substrate (CF, Color Filter), a lower substrate (TFT, Thin Film Transistor), and liquid crystal (LC) interposed between the upper substrate and the lower substrate, and a sealant. A general manufacturing process comprises a front stage of array process (including thin film, yellow light, etching, and film stripping), an intermediate stage of cell process (including bonding TFT substrate and the CF substrate), and a rear stage of assembling process (including mounting drive ICs and printed circuit board). The front stage of array process generally makes the TFT substrate for controlling the movement of liquid crystal molecules. The intermediate stage of cell process generally introduces liquid crystal between the TFT substrate and the CF substrate. The rear stage of assembling process generally mounts the drive ICs and combining the printed circuit board to effect driving the liquid crystal molecules to rotate for displaying images.
The substrates that have received liquid crystal filled therein are irradiated by ultraviolet light (UV1) for alignment in a high voltage activated (HVA) process and are subjected to inspection by automated optical inspection (AOI) to identify the result of alignment. Both UV1 or AOI need a pin of a probe to contact, in a one by one manner, panel inspection signal input pads of the TFT substrate to apply a voltage to the liquid crystal. The probe comprises a block corresponding to the TFT substrate and the block carries a pin that corresponds to the panel inspection signal input pads of the TFT substrate in order to effect application of voltage. The currently used probe can be classified in two types:
(1) Elevating type probe: The probe is first moved to a location below a panel inspection signal input pad of the TFT substrate and then the probe is elevated until the pin contacts the panel inspection signal input pad of the TFT substrate. Afterwards, a voltage is applied to carry out the HVA process and the AOI inspection.
(2) Clamping type probe: The probe first elevated to the level of the TFT substrate and then the probe is moved forward to the location of the panel inspection signal input pad of the TFT substrate. Afterwards, upper and lower portions of the block simultaneously clamp the TFT substrate and the pin contacts the panel inspection signal input pad of the TFT substrate. A voltage is then applied to carry out the HVA process and the AOI inspection.
However, both the elevating type probe and the clamping type probe show the following shortcomings. Each probe can be operated to apply voltage to a specific size of the TFT substrate. Since different TFT substrates have different locations to receive the applied voltage, the makes it necessary for the location of the pin on the associated block to be different. Consequently, array checker facility must change probes for handling different sizes of the TFT substrates and the contact between the pin and the TFT substrate and output of voltage must be re-identified. This is a waste of production line time and causes an increased load to the production line and is susceptible to replacement of incorrect probes. In addition, potential risk of impact may occur in the process of probe replacement.